Institut National de la Santé et de la Recherche Médicale, Centre for Research in Epidemiology and Population Health, CESP, U1018, Diabetes, Obesity, and Chronic Kidney Disease Epidemiology Team, 94807 Villejuif, France.
J Clin Endocrinol Metab. 2013 Jul;98(7):2922-8. doi: 10.1210/jc.2013-1294. Epub 2013 Apr 30.
Vitamin D deficiency is common in patients with chronic kidney disease (CKD). Current guidelines recommend treatment strategies in these patients similar to those for the general population, but the vitamin D nutritional status sufficient to prevent PTH levels from increasing in CKD is unknown. OBJECTIVE, MAIN OUTCOME MEASURE: Our aim was to study the relation between circulating PTH and 25(OH)D levels and to search for a 25(OH)D threshold associated with a significant PTH increase.
DESIGN, SETTING, AND PATIENTS: In the hospital-referred NephroTest cohort study, we measured 25(OH)D, PTH, and glomerular filtration rate (mGFR) by ⁵¹Cr-EDTA renal clearance in 929 adult patients with nondialysis CKD stages 1 to 5 and no vitamin D supplementation. Patients' mean age was 60.1 ± 14.7 years; 71% were men, and 9% were black. Their median mGFR was 37.8 mL/min/1.73 m².
We found a 25(OH)D threshold of 8 ng/mL with an upper limit of 20 ng/mL (95% confidence interval) by linear piecewise regression modeling of log-PTH for 25(OH)D adjusted for mGFR, age, race, and ionized calcium level. The smoothed curve confirmed that PTH concentration rose steeply when circulating 25(OH)D levels fell to less than 20 ng/mL.
Spontaneous 25(OH)D levels greater than 20 ng/mL seem sufficient to control serum PTH in CKD patients. This result reinforces guidelines to supplement vitamin D only if less than 30 ng/mL.
维生素 D 缺乏在慢性肾脏病（CKD）患者中很常见。目前的指南建议这些患者的治疗策略与普通人群相似，但预防 CKD 患者甲状旁腺激素（PTH）水平升高所需的维生素 D 营养状态尚不清楚。目的、主要观察指标：我们旨在研究循环 PTH 与 25（OH）D 水平之间的关系，并寻找与 PTH 显著升高相关的 25（OH）D 阈值。设计、地点和患者：在医院转诊的 NephroTest 队列研究中，我们通过 ⁵¹Cr-EDTA 肾清除率测量了 929 例非透析 CKD 1 至 5 期且无维生素 D 补充的成年患者的 25（OH）D、PTH 和肾小球滤过率（mGFR）。患者的平均年龄为 60.1 ± 14.7 岁；71%为男性，9%为黑人。他们的中位 mGFR 为 37.8 mL/min/1.73 m²。结果：我们通过线性分段回归模型对 25（OH）D 进行了对数-PTH 建模，调整了 mGFR、年龄、种族和离子钙水平，发现 25（OH）D 的阈值为 8ng/mL，上限为 20ng/mL（95%置信区间）。平滑曲线证实，当循环 25（OH）D 水平降至 20ng/mL 以下时，PTH 浓度急剧上升。结论：自发 25（OH）D 水平大于 20ng/mL 似乎足以控制 CKD 患者的血清 PTH。这一结果强化了仅在低于 30ng/mL 时补充维生素 D 的指南。
